Move gitmkstemps to path.c

[git.git] / path.c

diff --git a/path.c b/path.c
index 79aa104712364a8c18964feecd4c8079449a78cf..ab2e3687ab1c58c4a9e87679093208a701a0bfbd 100644 (file)
--- a/path.c
+++ b/path.c
@@ -157,6 +157,75 @@ int git_mkstemps(char *path, size_t len, const char *template, int suffix_len)
        return mkstemps(path, suffix_len);
 }
 
+/* Adapted from libiberty's mkstemp.c. */
+
+#undef TMP_MAX
+#define TMP_MAX 16384
+
+int gitmkstemps(char *pattern, int suffix_len)
+{
+       static const char letters[] =
+               "abcdefghijklmnopqrstuvwxyz"
+               "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+               "0123456789";
+       static const int num_letters = 62;
+       uint64_t value;
+       struct timeval tv;
+       char *template;
+       size_t len;
+       int fd, count;
+
+       len = strlen(pattern);
+
+       if (len < 6 + suffix_len) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       if (strncmp(&pattern[len - 6 - suffix_len], "XXXXXX", 6)) {
+               errno = EINVAL;
+               return -1;
+       }
+
+       /*
+        * Replace pattern's XXXXXX characters with randomness.
+        * Try TMP_MAX different filenames.
+        */
+       gettimeofday(&tv, NULL);
+       value = ((size_t)(tv.tv_usec << 16)) ^ tv.tv_sec ^ getpid();
+       template = &pattern[len - 6 - suffix_len];
+       for (count = 0; count < TMP_MAX; ++count) {
+               uint64_t v = value;
+               /* Fill in the random bits. */
+               template[0] = letters[v % num_letters]; v /= num_letters;
+               template[1] = letters[v % num_letters]; v /= num_letters;
+               template[2] = letters[v % num_letters]; v /= num_letters;
+               template[3] = letters[v % num_letters]; v /= num_letters;
+               template[4] = letters[v % num_letters]; v /= num_letters;
+               template[5] = letters[v % num_letters]; v /= num_letters;
+
+               fd = open(pattern, O_CREAT | O_EXCL | O_RDWR, 0600);
+               if (fd > 0)
+                       return fd;
+               /*
+                * Fatal error (EPERM, ENOSPC etc).
+                * It doesn't make sense to loop.
+                */
+               if (errno != EEXIST)
+                       break;
+               /*
+                * This is a random value.  It is only necessary that
+                * the next TMP_MAX values generated by adding 7777 to
+                * VALUE are different with (module 2^32).
+                */
+               value += 7777;
+       }
+       /* We return the null string if we can't find a unique file name.  */
+       pattern[0] = '\0';
+       errno = EINVAL;
+       return -1;
+}
+
 int validate_headref(const char *path)
 {
        struct stat st;